1. Field
Example embodiments relate to a non-volatile memory device having a threshold switching resistor, a memory array including the non-volatile memory device, and methods of manufacturing the same.
2. Description of the Related Art
A semiconductor memory array may include a plurality of unit memory cells that are connected to each other using circuits. In a dynamic random access memory (DRAM) that is an example of a semiconductor memory device, a unit memory cell may include a switch and a capacitor. The DRAM may be highly integrated and may operate at an increased speed. However, when the power is turned off, the data stored in the DRAM may be lost.
In order to solve this problem, non-volatile memory devices, which may preserve the stored data after the power is turned off (for example, flash memories), have been developed. Because flash memory is non-volatile, flash memory has a relatively low degree of integration and operates slower than a DRAM. In the field of non-volatile memory devices, research is being performed in the fields of Magnetic Random Access Memory (MRAM), Ferroelectric Random Access Memory (FRAM), Phase-change Random Access Memory (PRAM), and Resistance Random Access Memory (RRAM).
MRAM stores data using a characteristic of varying magnetization direction at a tunnel junction. FRAM stores data using a polarity property of ferroelectrics. PRAM stores data using a change in resistance value in accordance with the phase change of a specific material, and may include a resistor and a switching device. RRAM mainly uses a characteristic of a transition metal oxide, for example, a characteristic of varying resistance with respect to an applied voltage, and may include a resistor and a switching device.
A transistor or diode may be used as the switching device for such non-volatile memory devices. The transistor may include a source and drain doped with a conductive impurity and a gate laminate structure formed on a channel region between the source and drain. A diode having a switching function may be used instead of the transistor. The diode may have a p-n junction structure.
In order to improve a degree of integration, the size of the transistor and diode may be reduced. Reduction in the size of the transistor may results in reduction in current flow between the source and drain, and thus switching may not be easily carried out. As a result, data may not be recorded or deleted.